New Prognostic Marker For Breast Cancer

Scientists have identified a genetic variant that strongly predicts poor survival among women with breast cancer, particularly after treatment with a commonly used form of chemotherapy, according to a study published online in Nature Genetics.

The enzyme NQO1 protects cells from the damaging effects of oxidative stress. A common variant of NQO1 called NQO1*2, present in 4-20% of the human population, effectively eliminates production of the enzyme. Heli Nevanlinna, Jiri Bartek and colleagues carried out the first study investigating the NQO1*2 as a predictive factor for treatment in breast cancer by genotyping over 2,000 women with breast cancer in Finland and following the outcome of their disease and treatment.

Women with two copies of NQO1*2 who were treated with the drug epirubicin had a survival rate of only 17%, compared to 75% for women who had no copies or one copy of the NQO1*2 variant. The presence of NQO1*2 also had a significant effect on survival after metastasis. Given the large number of individuals who carry NQO1*2 -- up to 20% in Asian populations -- the authors suggest that NQO1 genotype could be an important predictive factor for treatment. They call for a randomized prospective clinical trial comparing epirubicin treatment with alternatives to validate the predictive potential of NQO1*2.